In a typical Internet Protocol multimedia subsystem (IMS) 3GPP/3GPP2 (third generation General Partnership Project) radio communication system, a Mobile Station (MS) sends a session initiation protocol (SIP) INVITE message to request that SIP session control be passed from a Serving Call Session Control Function (S-CSCF) to an application server (AS) to provide services to the Mobile Station. Previous methods used in Internet Protocol multimedia subsystems (IMS) require that the INVITE message be routed from the proxy server to the home server (I/S-CSCF) of the Mobile Station and then forwarded to the application server (AS).
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions, sizing, and/or relative placement of some of the elements in the figures may be exaggerated relative to other elements to clarify distinctive features of the illustrated embodiments. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of the illustrated embodiments.